Successful use of heparin and warfarin in the treatment of cholesterol crystal embolization

Intravenous Glu-plasminogen attenuates cholesterol crystal embolism-induced thrombotic angiopathy, acute kidney injury and kidney infarction

BACKGROUND

Cholesterol crystal (CC) embolism causes acute kidney injury (AKI) and ischaemic cortical necrosis associated with high mortality. We speculated that sustaining the fibrinolytic system with Glu-plasminogen (Glu-Plg) could be a safe way to attenuate AKI and prevent ischaemic infarction upon CC embolism.

METHODS

We induced CC embolism by injecting CC into the left kidney artery of C57BL/6J mice. The primary endpoint was glomerular filtration rate (GFR).

RESULTS

Starting as early as 2 h after CC embolism, thrombotic angiopathy progressed gradually in the interlobular, arcuate and interlobar arteries. This was associated with a decrease of GFR reaching a peak at 18 h, i.e. AKI, and progressive ischaemic kidney necrosis developing between 12-48 h after CC injection. Human plasma Glu-Plg extracts injected intravenously 4 h after CC embolism attenuated thrombotic angiopathy, GFR loss as well as ischaemic necrosis in a dose-dependent manner. No bleeding complications occurred after Glu-Plg injection. Injection of an intermediate dose (0.6 mg/kg) had only a transient protective effect on microvascular occlusions lasting for a few hours without a sustained protective effect on AKI at 18-48 h or cortical necrosis, while 1.5 mg/kg were fully protective. Importantly, no bleeding complications occurred.

CONCLUSIONS

These results provide the first experimental evidence that Glu-Plg could be an innovative therapeutic strategy to attenuate thrombotic angiopathy, AKI, kidney necrosis and potentially other clinical manifestations of CC embolism syndrome.

Crystal Clots as Therapeutic Target in Cholesterol Crystal Embolism

RATIONALE

Cholesterol crystal embolism can be a life-threatening complication of advanced atherosclerosis. Pathophysiology and molecular targets for treatment are largely unknown.

OBJECTIVE

We aimed to develop a new animal model of cholesterol crystal embolism to dissect the molecular mechanisms of cholesterol crystal (CC)-driven arterial occlusion, tissue infarction, and organ failure.

METHODS AND RESULTS

C57BL/6J mice were injected with CC into the left kidney artery. Primary end point was glomerular filtration rate (GFR). CC caused crystal clots occluding intrarenal arteries and a dose-dependent drop in GFR, followed by GFR recovery within 4 weeks, that is, acute kidney disease. In contrast, the extent of kidney infarction was more variable. Blocking necroptosis using mixed lineage kinase domain-like deficient mice or necrostatin-1s treatment protected from kidney infarction but not from GFR loss because arterial obstructions persisted, identifying crystal clots as a primary target to prevent organ failure. CC involved platelets, neutrophils, fibrin, and extracellular DNA. Neutrophil depletion or inhibition of the release of neutrophil extracellular traps had little effects, but platelet P2Y12 receptor antagonism with clopidogrel, fibrinolysis with urokinase, or DNA digestion with recombinant DNase I all prevented arterial occlusions, GFR loss, and kidney infarction. The window-of-opportunity was <3 hours after CC injection. However, combining Nec-1s (necrostatin-1s) prophylaxis given 1 hour before and DNase I 3 hours after CC injection completely prevented kidney failure and infarcts. In vitro, CC did not directly induce plasmatic coagulation but induced neutrophil extracellular trap formation and DNA release mainly from kidney endothelial cells, neutrophils, and few from platelets. CC induced ATP release from aggregating platelets, which increased fibrin formation in a DNase-dependent manner.

CONCLUSIONS

CC embolism causes arterial obstructions and organ failure via the formation of crystal clots with fibrin, platelets, and extracellular DNA as critical components. Therefore, our model enables to unravel the pathogenesis of the CC embolism syndrome as a basis for both prophylaxis and targeted therapy.

Performing Anticoagulation: A Puzzling Case of Cholesterol Embolization Syndrome

The avoidance of any form of anticoagulation is advised in cases of cholesterol embolization syndrome (CES). We herein describe a case of CES in a man with a history of unprovoked pulmonary embolism for which warfarinization was performed. Despite anecdotal reports of successful anticoagulation in CES patients with certain indications, irreversible renal failure, which was sufficiently severe to require chronic hemodialysis, eventually developed in our patient. Our results emphasize the pitfalls of this procedure, which imply its limited feasibility and safety. Several therapeutic concerns associated with this case are also discussed.

Cutaneous reactive angiomatosis associated with cholesterol embolism

Cholesterol embolism (CE) is characterized by emboli containing cholesterol crystal in the arterioles, most commonly found in the skin and the kidney. The skin presentations of CE include livedo reticularis, blue toe syndrome, ulceration and gangrene. Cutaneous reactive angiomatosis (CRA) is a recently proposed term to describe a group of reactive vascular proliferation in skin caused by various diseases. Its occurrence in association with CE is extremely uncommon. An 82-year-old man with a history of cerebral infarction and on long-term warfarin therapy developed progressive, multiple violaceous papules and nodules on the dorsal feet, soles and toes, simulating Kaposi's sarcoma. Skin biopsy showed marked vascular endothelial cell proliferations characteristic of CRA affecting the full thickness of dermis. In addition, cholesterol crystal emboli were found in dermal arterioles. The skin lesions improved after the warfarin dose was reduced. We emphasize the possible presence of CE in a patient presented with CRA, especially in those with a pre-existing atherosclerotic disease, on anticoagulation therapy, or having a prior history of invasive vascular procedure.